The present invention relates to a fluid apparatus which has a bellows, and which is typified by a bellows type pump and an accumulator for reducing pulsations of such a pump.
As a pump for circulating and transporting chemical liquid in various processes such as washing of surfaces of ICs or liquid crystal display devices in a semiconductor producing apparatus, used is a bellows type pump in which no particles are generated as a result of the pumping operation (for example, Japanese Patent Application Laying-Open No. 3-179184). In a pump of this kind, pulsations are produced by reciprocal motion due to extension and contraction of the bellows. In order to reduce the pulsations, therefore, also an accumulator is used (for example, Japanese Patent Application Laying-Open No. 10-196521).
In such a pump having a bellows, there arises no problem when chemical liquids or pure water are used as transported liquid. However, a problem is produced in the case where abrasive liquid containing slurry such as silica is used as a polishing solution for Chemical Mechanical Polishing (CMP) of a semiconductor wafer, a hard disk which is to be incorporated into a computer, and the like.
Namely, in the pump, the bellows which is extendingly and contractingly deformable in the axial direction is placed with setting the axis lateral. In the case where liquid containing a material such as slurry which sediments is used, therefore, the sedimenting material easily collects and sets in an extending and contracting portion of a lower semicircular portion in the bellows, thereby causing the bellows to be broken.
A suction port and a discharge port for liquid are disposed in the pump, and a suction check valve and a discharge check valve are disposed in the suction port and the discharge port, respectively. Each of the suction check valve and the discharge check valve is configured by, in addition to a valve element, incorporating a coil spring for pressing against a valve seat into a valve casing. In the case where liquid containing a material such as slurry which easily sediments is used, therefore, there arise problems such as that the sedimenting material easily collects and sets inside the coil spring of the suction check valve or the discharge check valve, and the pressing force due to the coil spring is not adequately applied to the valve element, so that the normal opening and closing performance of the valve is not obtained, and that sedimentation collects and aggregates inside the coil spring and the shape of particles of the sedimentation is changed from that of the initial stage, thereby adversely affecting polishing.
It is an object of the invention to provide a fluid apparatus having a bellows in which, eve in the case where transported liquid containing a sedimenting material such as slurry is used, the sedimenting material can be prevented from stagnating and collecting in an extending and contracting portion of the bellows and inside a suction check valve and a discharge check valve.
Disclosure of Invention
The fluid apparatus having a bellows according to the invention is a fluid apparatus configured by a pump in which a bellows that is extendingly and contractingly deformable in an axial direction is placed in a pump body with setting an axis B vertical to be driven to perform extending and contracting deformation, and form a liquid chamber inside the bellows, a suction port and a discharge port are formed in an inner bottom face of the pump body facing the liquid chamber, the suction port and the discharge port communicating with an inflow passage and an outflow passage which are disposed in the pump body, respectively, a suction ball type check valve and a discharge ball type check valve are disposed in the inflow passage and the outflow passage, respectively, liquid is sucked from the suction port via the suction ball type check valve into the liquid chamber by extension of the bellows, and the liquid in the liquid chamber is discharged from the discharge port via the discharge ball type check valve by contraction of the bellows. In the fluid apparatus, each of the suction ball type check valve and the discharge ball type check valve is configured so that a cylindrical valve casing is disposed with setting an axis vertical, and a ball valve element is caused by own weight to be closely contacted with a valve seat in the valve casing, thereby preventing liquid from reversely flowing.
In this case, the inner bottom face of the liquid chamber may be formed into a shape in which the face is downward inclined as moving toward the discharge port.
In the thus configured pump, the axis of the bellows in the pump body is set to be vertical. Even in the case where liquid containing a sedimenting material such as slurry is used, therefore, the sedimenting material can be prevented as far as possible from staying in an extending and contracting portion of the bellows.
Each of the suction ball type check valve and the discharge ball type check valve is configured so that the valve casing is vertically disposed, and the ball valve element is caused by its own weight to be closely contacted with the valve seat in the valve casing, thereby preventing liquid from reversely flowing. Even in the case where liquid containing a sedimenting material such as slurry is used, therefore, the sedimenting material can be prevented from stagnating and aggregating inside each of the check valves.
When the inner bottom face of the liquid chamber is formed into a shape in which the face is downward inclined as moving toward the discharge port, also liquid containing a sedimenting material such as slurry can be smoothly discharged along the downward inclined face of the inner bottom face toward the discharge port.
The other fluid apparatus having a bellows according to the invention is a fluid apparatus configured by a pump and an accumulator in which the pump is configured so that a bellows lows that is extendingly and contractingly deformable in an axial direction is placed in a pump body with setting an axis vertical to be driven to perform extending and contracting deformation, and form a liquid chamber inside the bellows, a suction port and a discharge port are formed in an inner bottom face of the pump body facing the liquid chamber, the suction port and the discharge port communicating with an inflow passage and an outflow passage which are disposed in the pump body, respectively, a suction ball type check valve is disposed in the suction port, liquid is sucked from the suction port via the suction ball type check valve into the liquid chamber by extension of the bellows, and the liquid in the liquid chamber is discharged from the discharge port by contraction of the bellows; the accumulator is configured so that a bellows that is extendingly and contractingly deformable in an axial direction is placed in an accumulator body with setting an axis vertical to separately form a liquid chamber inside the bellows and an air chamber outside the bellows, an inflow port and an outflow port are disposed in an inner bottom face of the accumulator body facing the liquid chamber, the inflow port communicating with a downstream end of the outflow passage, pulsations caused by a discharge pressure of the liquid discharged from the liquid chamber of the pump is damped by a capacity change of the liquid chamber due to extending and contracting deformation of the bellows of the accumulator, and a discharge ball type check valve of the pump is disposed in the inflow port; and each of the suction ball type check valve and the discharge ball type check valve is configured so that a cylindrical valve casing is disposed with setting an axis vertical, and a ball valve element is caused by own weight to be closely contacted with a valve seat in the valve casing, thereby preventing liquid from reversely flowing.
In this case, the inner bottom face of the liquid chamber of the pump may be formed into a shape in which the face is downward inclined as moving toward the discharge port. The inner bottom face of the liquid chamber of the accumulator may be formed into a shape in which the face is downward inclined as moving toward the outflow port.
In the pump juxtaposed with the accumulator, pulsations of the pump can be reduced. In the same manner as the pump described above, furthermore, the axis of the bellows in the accumulator body is set to be vertical. Even in the case where liquid containing a sedimenting material such as slurry is used, therefore, the sedimenting material can be prevented as far as possible from staying in an extending and contracting portion of the bellows.
Each of the suction ball type check valve and the discharge ball type check valve is configured so that the valve casing is vertically disposed, and the ball valve element is caused by its own weight to be closely contacted with the valve seat in the valve casing, thereby preventing liquid from reversely flowing. Even in the case where liquid containing a sedimenting material such as slurry is used, therefore, the sedimenting material can be prevented from stagnating and aggregating inside each of the check valves.
The suction ball type check valve of the pump is disposed in the pump, but the discharge ball type check valve is disposed inside the accumulator. As compared with the case where both the suction ball type check valve and the discharge ball type check valve are disposed in the pump, therefore, the interior of the pump can be reduced by a degree corresponding to the volume occupied by the discharge ball type check valve, so that the pump can be made compact.
In the pump, as described above, when the inner bottom face of the liquid chamber is formed into a shape in which the face is downward inclined as moving toward the discharge port, also liquid containing a sedimenting material such as slurry can be smoothly discharged along the downward inclined face of the inner bottom face toward the discharge port, and the sedimenting material can be prevented from collecting and setting on the inner bottom face. In the accumulator also, when the inner bottom face of the liquid chamber is formed into a shape in which the face is downward inclined as moving toward the outflow port, also liquid containing a sedimenting material such as slurry can be smoothly discharged along the downward inclined face of the inner bottom face toward the outflow port, and the sedimenting material can be prevented from collecting and setting on the inner bottom face.